4:00 PM CDT Saturday, 9 October 2010 Update
West Caribbean Invest 98L has been improving in structure quite a bit today, and a tropical cyclone could be forming this weekend. The National Hurricane Center earlier today put up a now seemingly conservative 30% probability of tropical cyclone formation within the next 48 hours ("Code Orange") for this disturbance.

Invest 98L consists of developing low and mid level centers, which appear to be fairly well colocated, in the vicinity of 13N and 80W. Some curved convective banding is noted in the western half of the disturbance, and back-of-the-envelope real-time Dvoark Current Intensity may already be close to T1.5 or better.

Sea surface temperatures in this region are still quite warm, and shear is not prohibitive. Indeed, shear looks to be easing while the atmosphere is also moistening up (all this being more conducive for further development). Movement seems to be net-net generally to the west, after some earlier center of circulation jumps and/or meanderings.

Interests from central America to the Yucatan peninsula, and possibly also from Cuba and into the GOM, may wish to be on the alert for the potential tropical cyclone formation, and any watches and warnings that may be issued for these areas, as at this early stage, it is very unclear which direction 98L will ultimately take. On one hand, interaction with central America could ultimately cut its development short. On the other, 98L could begin edging more to the northwest, or even to the north in time, and thus spend a good deal longer over water. Models should start having a better handle on its future track by this time tomorrow.

-Cieldumort

11:00 AM EDT Friday, 8 October 2010 Update
Otto has been upgraded to a Hurricane, and will likely remain so through the weekend, it's path takes it far away from any land areas. It is expected to transition to extratropical Monday and near the azores then.

The area in the west Caribbean still has about a 20% chance for development. It's best chance for development is probably late Monday, if it does at all. Those in western Cuba, Jamaica, and the Caymans will want to watch it the most. It isn't likely to affect the US.

Otto continues to strengthen and has a shot at becoming a hurricane before hitting the worst of the shear, it will stay away from land until it becomes extratropical, where it may affect the Azores.

If Otto were to become a hurricane, it would likely be tonight or tomorrow, after which chances go down.

The area in the western Caribbean has a 10% chance to develop now, and it's most likely development period is Sunday or Monday.. If it does develop the most likely scenario is that it will slowly move into the Yucatan and rain. There is a slight chance it could get "picked up" by something further north that would bring it across Cuba, although most likely it will stay east of Florida, or most of the convection will anyway. It is what to watch over the weekend.

Subtropical Depression 17 has formed northeast of the Caribbean, it is expected to drift slowly north and northwest for a bit then race out to sea to the northeast. This system will very likely be no threat to land.

Subtropical storms tend to hand stronger winds away from the center, but they still do have some tropical like characteristics near the center. This system has a good shot at becoming purely tropical before hitting the bump to the east. It won't likely be anything more than a mid wind-range Tropical storm.

Chances have risen for development of 97L, which peaks tomorrow, it is over the northeastern Caribbean sea bringing rainfall to the islands. It is still forecast to move away from the United States.

The western Caribbean may still have something in it next week, but the current pattern around the Gulf resembles more November than October this year, s

Original Update
So far the wave in the northeastern Caribbean (97L) has not developed, and conditions got worse for it as it approached the islands. It still has a chance to cause rainfall along the Caribbean islands, and still has a chance to develop, 20% now, but that improves later in the week. However any development is likely to recurve out to sea before it reaches the continental United States.

Another wave east of the Caribbean currently isn't being tracked as an invest area, but only has a 10% chance for development.

Activity from The west Caribbean won't likely be seen until next week.

There wasn't much change there all day. Things should be winding down now anyway. As the fronts come down and stall over the Gulf of Mexico and the Western Caribbean, those will become the areas to keep an eye on.

Update 10/5: It looks like 97L is being severely sheared to me this morning along with a considerable amount of dry air being pulled in on the western side. I'm thinking that 60% is a bit high for development there. That new blob of convection in the Caribbean might gain some traction later in the week.

Yep, 97L not fairing well given shear. Area of convection in the Bahamas to the east of Miami (not an invest ATM), associated with the front that pushed through Florida and pulled up stationary will likely have same fate given the flow.

What about the area of convection in the Caribbean south of Hispanola this morning? Not an invest ATM, but this is a region where I'd expect some development if it persists.

97L looking like it's trying to develop, albeit sub-tropical in appearance. Even so, could easily shake it off and become entirely tropical. Outside of the dangerous flooding potential for P.R. and Lesser Antilles, seems like only possibly of risk might be to a few thousand snapper, yellow tail, and the like.

As previously mentioned, the area south of Eastern Haiti is not only very convective, but would appear to possibly be showing hints of some rotation ( at some level ). The upper level winds are no doubt seemingly beginning to relent, and actually a good deal less hostile than what 97L is currently dealing with.

I agree that 97L looks to be more subtropical in organization. A lot of dry air entrainment from the western side and still a significant amount of shear. If it develops, I would think that it would be subtropical rather than purely tropical. The models are developing 97L and moving it northeastward and they are indicating something forming in the western Caribbean late in the period 5 - 7 days from now.

Supportive SST's still lingering ITVO the Florida peninsula... I recorded a surf water temperature of 81.2F in south NSB Sunday afternoon. Looks like SST's near the convective complex in the Caribbean are just below seasonal peaks: buoy # 42059 reporting 85.3F this afternoon with a baro of 29.77". Note the moderate to strong/increasing west wind past 12 hours.

Sounds like perhaps a weak LLC may be attempting to organize south of Hispanola. Perhaps we have 97L and 97L"b" competing for inflow here. This afternoons satellite indicates that the Cirrus blow off in the central Caribbean sure looks to be light and almost variable.

However this system evolves it won't be tropical to start. An approach to the US is zero; winds aloft are well over 80 knots at the core...that takes care of that scenario. There is an upper high above the system itself so winds are light right over the top and marginal along the projected track. It looks pretty on satellite but that's it.

Looks like we Have Otto at 5PM, Not much else has changed, Recon is finding pressures around 991 or so. And I don't think there is any reason to expect the track to change. Sub-Tropical systems aren't terribly common, so it's interesting to see the structural differences between it and a fully tropical system.

One thing for sure, though sub-tropical in nature and with the enormous feed from the Pacific ITCZ, I would have little doubt that given time we'd see an eventual crossover to fully tropical. Entirely academic however and the good news is that it's simply waiting for it's "train pass" from the short wave railway to the N. Atlantic.

There seems to be a LLC or MLC forming just north of Panama. Convection is not looking to impressive at the moment. Being October and climatalogically prime for this area of the Caribbean, keeping an eye on it.

I think we will have Tropical Depression 18 very soon because it is organizing pretty quickly. By the way, it has been Invest 98L since yesterday evening. That is when the initial Skeetobite model runs began on this disturbance.

Recent satellite imagery is indicating a decrease in the convection in the western band and a CHT, convective hot tower, developing to the NE of the CoC.
Almost appeared to be a shift in power... drawing energy from the western convective band and building the CHT near the center.
Current CoC near 13.0N/ 81.0W, using the wv loop. Or about 45 miles ENE of San Andreas Island.
Current CHT near 13.2N/ 80.4W

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